let list = [23, 21, 34, 24, 51, 63]
const array1 = ['a', 'b', 'c', 'd']
const array2 = ['d', 'e', 'f']

/**
 * push
 * pop
 * unshift
 * shift
 * splice
 * slice
 * join
 * concat
 * forEach
 * map
 * reduce
 * filter
 * every
 * some
 * find
 * findIndex
 * indexOf
 * lastIndexOf
 * includes
 */
